Really Scary Transmission Problem!

[BeauBlues]

So I started getting really bad vibes from transmission starting a little while ago, about a month. The problem was that the shifter would kick, pretty violently, when I press on the gas. Mostly does it in gears 1,2,3,5. But its mostly noticable in 2nd gear.

Anyway, that little problem, kind of got ignored by me, because the car is my daily driver its been hard to find a good amount of time to find a problem. So, yesterday I was driving to work, when all of a sudden the shifter popped really violently out of fourth and the car slowed down a whole lot on its own. I tried to shifter back into any gear with no avail. Just got a lot of grinding and other weird scary feelings and noises. Even when coasting with the car in neutral, the car was stuttering and jolting with some vibrations.

So with the clutch in I coasted to the side and stopped to catch my breath. I then tried shifting through all the gears, and surely they all started to shift soomewhat ok. And it would let me drive again just like normal. This problem has happened twice so far and I now notice a faint random kicking feeling coming from the transmission when the car is in neutral sitting still.

Can anyone help me on this, I need ALL possible senarios for the problem before this turns into some WAY worse. Keep in mind this is my daily driver, so if Im going to fix this, Ive got to do it quick and I would like as much input as possible.

[BeauBlues]

Oh I forgot to mention that the transmission was rebuilt about a year ago. Im not sure if this rules out another rebuild possibility.

[450knotOffice]

I can't offer any help to you Beau, but I hope the problem is a simple and inexpensive one.

Good luck buddy.

[s5uewf]

It sounds like you notice it when you are stopped and in neutral, as well as when you are moving. If this is true, then it sounds like you can at least eliminate ring and pinion gear issues.

If you feel a recurring knock or thump or similar even when you
are stopped and in neutral, then I think you need to start considering items which are rotating even when no gear and no gear contact is being made. I hope others kick in, but I believe this will start to indicate that at least something along the lines of shaft bearing(s), synchro are implicated.

Hopefully someone with more direct knowledge will chime in.

Good luck.

[Grady Clay]

OK, first confirm that the two engine mount and two transmission mount bolts are all in place and tight. Also check the connections between the mounts and the engine & transmission. Next check all four nuts that attach the engine to the transmission. The one at the starter is difficult to get to but worth checking. Disconnect the battery when you are tightening this.

While under the car, check the clutch operation and the CV joint attachment. Put a torque wrench on all the CV bolts. Check on top of the transmission bell housing and in the little notch drain on the bottom for any signs of rubber chards. That could be a rubber-center clutch disc failing.

Grab the center of each axle and move it axially. It should be free to move about 1 cm and not be dependent on wheel rotation position. Check the CV boots not leaking grease.

Next would be to drain the transmission and inspect the magnet. Drain the oil through a paint filter so you don’t miss anything. Remove the shift pivot plate and see if there are any errant parts inside. (You will need a new gasket.) Don’t forget to refill with gear oil.

These are fairly severe symptoms and warrant immediate attention. You don’t want to damage expensive transmission internals or other. Post what was done at the transmission “rebuild.”

Best,
Grady

[john walker's workshop]

the violence you describe sounds more clutch related than from the transmission. did the car shudder violently in 1st as you let out the clutch to take off from a stop? loose engine to trans bolts/nuts can cause this too.

[BeauBlues]

Hey thanks for the replies so far...The rebuild was done by some shop that was handled through motormeister. Yes I know all about them and dont feel like discussing them in this situation. They were simply the middle man in the rebuild. Anyway the rebuild just involved replacing all broken and worn components, ie syncros, dog teeth, and other misc items.

And John, yes the car does shake taking off from first. Its done that for a long time, because bonehead me forgot to resurface the flywheel, but can that mistake lead into something serious like this. What Im asking is, if it is a clutch problem can you describe how it would cause my problem, ie cant select gears sometimes, kicking randomly in neutral. If it is the clutch, well I just hope its the clutch because another tranny rebuild is just too much to bear.

Oh and to answer another question from earlier, the clutch is spring centered not rubber.

[Grady Clay]

Oil on the clutch can cause these symptoms, usually not so severe. With oil on the clutch disc, there are two usual problems. First is the inconsistent clutch judder. Usually this is temperature sensitive. Second is the sticking of the clutch disc to either the pressure plate or flywheel when it should release. This prevents normal shifting because the stiction of the disc overwhelms the syncros.

The big deal of the clutch not releasing is damage to the syncros and dogs in the transmission. Of course severe judder can cause other problems. Most common is loosening of fasteners.

Best,
Grady

BTW, I can’t believe how often MM seems to be central to Porsche problems. Sad.
G.

[BeauBlues]

Early Morning bump for more help.

[ischmitz]

Oil from somewhere leaking onto the clutch disk. It sounds like the engine/tranny needs to come out for a closer look.

[BeauBlues]

Thats what I feared, but if it must... I will find time.

[quaz]

Hmmm I had a very similar problem with a pressure plate that had a broken strap. At idle if all things were sitting OK it would shift fine through all gears. As soon as you spun up the engine it would not shift at all. I wouldn't be surprised if something on the pressure plate let loose.

[BeauBlues]

Sorry if this is a dumb question, but where is there a strap on a pressure plate?

[Grady Clay]

If by “strap” you mean the link between the
pressure plate housing and the moveable
friction surface, check here at the end:

'70 clutch still broken, help needed to make race

This is a 2.2 but everything is common to much later.

Best,
Grady

[dick911]

Other possibility comes in sight while reading your problems:

The clutch fork can brake on the 915 tranny.

Most of the time it will not brake sudden, but slowly bend and braking after a while...

Good luck,

Dick

[quaz]

Originally posted by Grady Clay
If by “strap” you mean the link between the
pressure plate housing and the moveable
friction surface, check here at the end:

'70 clutch still broken, help needed to make race

This is a 2.2 but everything is common to much later.

Best,
Grady

That post refered to above is exactly what happened to me. It can cause some very weird things to happen. Sometimes the clutch will work, sometimes it won't. However you know something is not right for sure.

If the head of the rivit comes off and the strap can rotate out to the bell housing it can make some really cool noises as well.

[POKDUB]

I had the violant movement of the gear shift recently, and as Grady mentioned in his first post, the problem was with the mounting bolts supporting the transmission plate. Have you checked them like Grady suggested.

[PatrickB]

Beau...

How's the tranny working out? I have a recommendation for a shop in Fullerton, if you still need help...